story: An atoll (, , , , or ), sometimes called a coral atoll, is a ring-shaped coral reef including a coral rim that encircles a lagoon partially or completely. There may be coral islands/cays on the rim. The coral of the atoll often sits atop the rim of an extinct seamount or volcano which has eroded or subsided partially beneath the water. The lagoon forms over the volcanic crater or caldera while the higher rim remains above water or at shallow depths that permit the coral to grow and form the reefs. For the atoll to persist, continued erosion or subsidence must be at a rate slow enough to permit reef growth upwards and outwards to replace the lost height. 
  
  The word "atoll" comes from the Dhivehi (an Indo-Aryan language spoken on the Maldive Islands) word "atholhu" (Dhivehi: , ), meaning an administrative subdivision. Its first recorded use in English was in 1625 as "atollon" – Charles Darwin recognized its indigenous origin and coined, in his "The Structure and Distribution of Coral Reefs", the definition of atolls as "circular groups of coral islets" that is synonymous with "lagoon-island". 
  
  More modern definitions of "atoll" describe them as "annular reefs enclosing a lagoon in which there are no promontories other than reefs and islets composed of reef detritus" or "in an exclusively morphological sense, [as] a ring-shaped ribbon reef enclosing a lagoon".
questions: what kind of coral reef is discussed?
questions: what shape is it?
questions: what is another attribute?
questions: where is the coral?
questions: of what?
questions: above the water?
questions: what language does atoll come from?
questions: what word is it derived from?
questions: what does that mean?
questions: where is that language spoken?
questions: what is a modern meaning of atoll?
questions: when was it first used in English?
questions: by who?
questions: how did he describe it?
questions: what is it similar to?
questions: what word did he use for it?
answers: a coral atoll
answers:  a coral atoll, is a ring-shaped coral reef
answers: a ring
answers: is a ring-shaped coral reef
answers: it encircles a lagoon
answers: that encircles a lagoon
answers: atop the rim
answers: The coral of the atoll often sits atop the rim of an extinct seamount
answers: an extinct seamount or volcano
answers: the rim of an extinct seamount or volcano
answers: partially
answers: or subsided partially beneath the water
answers: Dhivehi
answers: "atoll" comes from the Dhivehi 
answers: "atholhu"
answers: from the Dhivehi (an Indo-Aryan language spoken on the Maldive Islands) word "atholhu"
answers: an administrative subdivision
answers: meaning an administrative subdivision
answers: the Maldive Islands
answers: spoken on the Maldive Islands
answers: annular reefs enclosing a lagoon
answers: modern definitions of "atoll" describe them as "annular reefs enclosing a lagoon
answers: in 1625
answers: Its first recorded use in English was in 1625
answers: Charles Darwin
answers: Charles Darwin
answers: "circular groups of coral islets"
answers: "circular groups of coral islets"
answers: "lagoon-island"
answers: that is synonymous with "lagoon-island"
answers: "atollon"
answers: "atollon" – Charles Darwin